The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Heat exchangers are used to exchange heat between two fluids. In the automotive industry, a heat exchanger in the form of a radiator is used to exchange heat between an engine cooling fluid and air. In addition, a heat exchanger is used to exchange heat between the engine coolant fluid and air to be blown into the passenger compartment to heat the air. Also, a heat exchanger in the form of a condenser is used to exchange heat between a refrigerant and air. Finally, a heat exchanger in the form of an evaporator is used to exchange heat between a refrigerant and air that is to be blown into the passenger compartment to cool the air.
Each of these heat exchangers includes a plurality of tubes through which a fluid flows, a plurality of fins arranged between adjacent tubes to be bonded to the tubes, a core plate connected to each longitudinal end of the plurality of tubes, a tank member disposed at each end of the plurality of tubes and an insert or side plate located at opposite sides of the plurality of tubes and fins. The inserts or side plates provide stability to the assembled heat exchanger.
Typically, the plurality of tubes and the inserts or side plates extend through apertures formed in each core plate and this assembly is brazed to maintain its integrity as well as to seal the interface between the tubes and the core plates and interface between the inserts or side plates and the core plates.
When both the insert or side plates and the plurality of tubes are brazed to the core plate, problems can occur due to thermal stress. In cold ambient temperatures and hot coolant conditions, the tubes want to expand due to their increased temperature due to the hot coolant. The inserts or side plates want to contract due to the cold ambient temperature. This creates relatively high stresses at the interfaces between the tubes and core plates and the interfaces between the inserts or side plates and the core plates. This high stress creates the potential for cracking and cooling leaks.